Dyspraxia Explained

Terminology

What is Dyspraxia ?

What Causes Dyspraxia ?

Verbal Dyspraxia

Research

Terminology

One of the most confusing things when trying to understand Dyspraxia is actually the terminology used, so we address this first to be clear on the information we provide.

The term ‘dyspraxia’ typically refers to developmental, or motor, dyspraxia, rather than verbal or oral dyspraxia (discussed below). Unfortunately, there is no clear definition of dyspraxia that enables it to be applied consistently, meaning it is often applied in different ways by different groups. It is also used interchangeably with a number of different terms, the most common of which is Developmental Coordination Disorder (DCD).

DCD is listed under the Neurodevelopmental Disorders category in the 5th version of Diagnostic and Statistical Manual of the American Psychiatric Association. It was endorsed as the preferred term at an international, multi-disciplinary consensus meeting in Canada in 1994 and more recently, by the European Academy of Childhood Disability [1]. The latter stated that there was no evidence for any difference between DCD and Dyspraxia.

On this website, we use the two terms interchangeably to describe the same condition as a reflection of practice within Australia, where both terms persist at a clinical level.

What is Dyspraxia

DCD (Dyspraxia) is a motor skill disorder which impacts upon an individual’s ability to perform either, or both, fine and gross motor skills. Fine motor skills include tasks like handwriting, tying shoelaces and buttoning a shirt. Gross motor skills include tasks like walking, running and climbing. Individuals with the disorder will have trouble with a mix of these skills compared to others of the same age, intelligence and level of experience and this trouble will have an impact on their ability to function at home, school and/or in the community.

The specific criteria defined by the American Psychiatric Association’s Diagnostic and Statistical Manual, 5th Ed. [2] are:

  1. Acquisition and execution of coordinated motor skills are below what would be expected at a given chronologic age and opportunity for skill learning and use; difficulties are manifested as clumsiness (e.g. dropping or bumping into objects) and as slowness and inaccuracy of performance of motor skills (e.g. catching an object, using scissors, handwriting, riding a bike, or participating in sports).
  2. The motor skills deficit significantly or persistently interferes with activities of daily living appropriate to the chronologic age (e.g. self-care and self-maintenance) and impacts academic/school productivity, prevocational and vocational activities, leisure and play.
  3. The onset of symptoms is early in the developmental period.
  4. The motor skills deficit cannot be better explained by intellectual disability or visual impairment and are not attributable to a neurologic condition affecting movement (e.g. cerebral palsy, muscular dystrophy, or a degenerative disorder).

A recent review by the European Academy of Childhood Disability [1] determined that approximately 5-6% of school-age children are affected. Boys are more commonly affected than girls, though the ration varies considerably from study to study – some suggest twice as many boys are affected while others say the ratio is closer to 7 boys for every girl. Though historically, some professionals dismissed the disorder as simply clumsiness that will be outgrown, the review by the Academy determined that between 50-70% of children fail to outgrow the disorder.

What causes Dyspraxia ?             back to top

There has been no single cause for DCD (Dyspraxia) identified. There is a lot of variability in DCD (Dyspraxia) – variability in severity, in the type of skills affected, in the area of control that is impacted (e.g. some children may have difficulty with planning movement while others may have difficulty sending the right messages within the brain and to the limbs to get them to move in the desired fashion), and in the presence or absence of associated disorders. This variability makes it hard for researchers because within any group that they study, it is rare that two children will present with the same make-up of these factors. We do know that there are factors that place a child at increased risk of developing DCD (Dyspraxia) and these are discussed below. There has also been a recent increase in the study of the brain and how it functions in DCD (Dyspraxia) and we also explain some of this below.

 

Risk factors

  1. Premature birth. The most recognised risk factor for DCD (Dyspraxia) is being born premature (less than 37 weeks gestation). A review study reported that an estimated 40.5% of children born preterm scored in the mild-moderate motor impairment range on standardised batteries, and 19% fell in the moderate-severe range [3]. This represents 2.5-4 times more children in these ranges than we would expect in an average sample of children. We also know that the percentage of children falling within the motor impaired range increases as gestational age decreases – i.e. there is a greater risk of developing DCD (Dyspraxia) when born at 28 weeks compared with being born at 34 weeks [4]. Some disagreement remains about whether a child born premature should be given the same DCD (Dypsraxia) diagnosis as a child born at term. The motor impairment we see in both is similar on the surface, but a child born premature is often exposed to a much higher number of pre- and post-birth complications – for example, their mother may have had an infection, they may have been in intensive care due to low oxygen, they may have been given steroids after birth. Exposure to such complications may result in later motor impairment that is different in origin to that seen in children who were born at term.
  2. Male gender. It is unclear why, but males are more likely to be diagnosed with DCD (Dyspraxia) than females. The ratio of males to females varies, with a recent review reporting ratios of between 2 to 7 males to each female [5].
  3. Small for gestational age (SGA). Children born at a weight considerably lower than that expected for their gestational age are considered SGA. This has found to be a risk factor for DCD (Dyspraxia) in children born at term, as well as those born premature [4]. SGA can be the result of smoking in pregnancy (this is not the only cause though) – maternal smoking has also been noted as a risk factor for DCD (Dyspraxia) [4].
  4. Genetics. A family history of clumsiness has long been considered a potential risk factor for DCD (Dypsraxia) [6], but it has only been more recently that geneticists have begun to quantify the genetic component of the disorder. Current estimates suggest that up to 70% of the variability we see in DCD (Dyspraxia) is linked to an individual’s genetic make-up [7], but much more work is needed in this area.
  5. Other factors. There are lots of other factors that could potentially impact on a child’s risk of developing DCD (Dyspraxia). These include, but are not limited to, environment, the socioeconomic status of the child’s family, nutrition, movement exposure and complications in pregnancy or early life.

 

Brain function in DCD (Dyspraxia)

Technology to study the structure and function of the brain is always improving. We are beginning to see research looking at the brain in DCD (Dyspraxia), but at this stage, the studies are typically very small and we still have a long way to go.

About the brain: To better understand what we know, it helps to understand a little bit about the brain itself. The brain is made up of millions of cell, or neurons. Each cell has a body, which can receive messages from other cells through little branches that extend from the body. It also has an axon, which looks like the other branches, but is much longer. This axon is used to send messages to other cells. This allows different parts of the brain to talk to each other. Why would they need to talk to each other?

The brain is divided into four lobes (frontal, parietal, occipital and temporal). The cerebellum is attached via an area of the brain stem, which runs from the brain down into the spinal cord. We know that some areas of the brain are move involved in some functions than others. For example, the frontal lobe plays a big part in the way we think. Toward the rear of the frontal lobe, there is an area called the motor cortex – this receives information from lots of areas of the brain and converts them into messages, sent via the spinal cord, to move our bodies. The parietal lobe interprets information received from our senses. The occipital lobe helps us understand what we see and the temporal lobe helps us understand what we hear.

These different areas of the brain need to communicate with each other to help us understand and navigate our lives. For example, to pour a glass of water, we need visual information to help us understand how far away the glass is, which will help us determine the muscles we need to move to reach for a glass. We need sensory information from the parietal lobe to tell us how heavy the glass is so that we can use the right amount of force to grasp the glass. And so on.

the structure of the brain in DCD (Dyspraxia): All areas of the brain and spinal cord contain two types of matter – grey and white. Grey matter contains the cell bodies and the message receiving branches of the cell. One recent study examined children with combined motor and attention deficits and found that the grey matter was thinner in some regions (frontal, parietal and temporal lobes) in children with deficits compared to those without [8]. This might mean that the cell bodies are smaller or there are less of them.

White matter contains the axons, or message sending branches of the cells. A new technology allows research to measure these pathways. Two small studies have indicated that there may be differences in the maturity or integrity of these pathways in DCD (Dyspraxia) [9, 10].

The function of the brain in DCD (Dyspraxia): Brain function can be explored by asking individuals with DCD (Dyspraxia) to complete set tasks within a brain scanner. Researchers can then analyse which areas of the brain are active and compare this pattern to that in individuals without impairment. Overall, the studies that have done this so far indicate that there are differences in brain activity in DCD (Dyspraxia), most often observed in areas of the brain known to contribute to motor function, such as the frontal and parietal lobes and the cerebellum [11].

When this is all pulled together, it appears that the brain of individuals with DCD (Dyspraxia) is not functioning in the same way as individuals without the disorder. Whether this is because there are fewer or smaller cells, or the pathways that send messages between the cells are less mature, or some other reason, is not certain and requires more research. The differences may result from any of the risk factors we discussed earlier, from another, not yet identified risk, or a combination.

Verbal Dyspraxia (CAS)

Verbal Dyspraxia, the medical term is Childhood Apraxia of Speech

for more information please download a factsheet     cas-factsheet

provided by:

The Centre of Research Excellence in Child Language is a collaboration of child speech and language experts. The Centre has developed this fact sheet with the key family support groups of Victoria and Queensland, and CASSA Inc.

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